1. Field
The present invention relates to a secondary battery.
2. Description of Related Art
Often a lithium secondary battery is formed by accommodating an electrode assembly in a can together with an electrolyte, the electrode assembly including a positive electrode plate, a negative electrode plate and a separator, hermetically sealing an upper opening of the can with a cap assembly, and coupling a cap plate of the cap assembly to the resulting can by welding the upper opening of the can.
Before coupling the cap plate of the cap assembly to the can, an insulation case may be inserted into the can to be on the electrode assembly and to prevent an electrical short between the electrode assembly and the cap assembly.
However, since the insulation case is seated on the electrode assembly, it may press against a top portion of the electrode assembly when the cap plate is welded to the can, preceded by folding the positive electrode tab and the negative electrode tab. If the top portion of the electrode assembly is pressed, the separator may deform, which may bring the positive electrode plate and the negative electrode plate into direct contact, resulting in an electrical short. Additionally, since the insulation case is not fixed at a specific location in the can, but rather is movable, it may not be accurately positioned in the electrode assembly, resulting in improper welding of the cap plate. In other words, the welding of the cap plate may be inconsistent.